They're all more versatile. Iggy's the only one I'm reluctant to call a better player due to his TOs and lower shooting percentages, but he's also a much, much better defender.
Let's just compare last season, shall we?
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What are the mains things that jump out at you? They all rebound at a better rate than him. They all get to the line at a better rate than him. They all commit less fouls while making more steals than him (hints towards being better defenders).
Yes, only Martin protects the ball noticeably better. Manu and Iggy turn it over at an alarming rate, but Rip is pretty bad, too. Not exactly a "win" for him.
Martin and G-Nobe flat out score more efficiently than Rip. They shoot just as good, but better with the 3s. They need less attempts to put up the numbers Rip does.
Aren't you a TS% guy? Guess who's the worst of 'em.. yep, Rip.
What about PER? He's even with Iggy, and a good distance from Martin and Ginobili.
WP48 your bag? Sure it's somewhat controversial, but what they heck. Rip posted a 0.070 last season, which is actually below average. Martin - .223 (very good), Iggy - .184 (pretty good), Ginobili - .311 (awesome).
There are a lot of close debates when comparing players, since there's a whole slew of factors. This one just isn't one of 'em.
Note: I actually like Rip quite a bit. He's a fine player.